U.S. Pat. No. 4,700,862, as owned by the Assignee hereof, illustrates therein a stackable bin which has met with significant commercial success, and which has proven highly desirable for permitting storage of product therein in such a fashion as to permit shipment between locations, and storage at a selected location. The stackable bin employs an upright hollow wall structure, normally a four-sided wall structure, which is removably positioned between upper and lower pallet-like supports. This wall structure is provided with four corner folds, and may optionally be provided with two intermediate folds to facilitate collapsing of the sidewall structure. Each sidewall of the sidewall structure is defined by a three-ply laminate defined by inner and outer layers fixedly and coextensively secured to opposite sides of an intermediate layer. The inner and outer layers each include inner and outer facing sheets joined by transversely extending ribs, with these inner and outer layers being preferably constructed of plastic formed as a profile extrusion. The intermediate layer is preferably of a light-weight rigid foam. The inner and outer layers are preferably oriented so that the ribs, and hence the tubular profiles defined by the ribs in the facing sheets, extend generally vertically. This prior art structure performed in a desirable manner, and has met with significant commercial success.
As an improvement to this prior art structure, the Assignee previously modified the sidewall structure so that, while the sidewalls were still of the same basic three-ply construction, nevertheless the one-ply corners were modified so as to be defined by a separate corner piece which was oriented so that the ribs or flutes projected horizontally, rather than vertically as in the device of U.S. Pat. No. 4,700,862.
In addition, this modified prior art structure was also sometimes provided with a metal reinforcing rod extending vertically thereof adjacent the end of each sidewall. This metal reinforcing rod was positioned within the three-ply construction, namely between the inner and outer layers, and was disposed directly between opposed ends of the intermediate foam layer and the one-ply corner member. This construction provided increased stacking strength, but still utilized the same three-ply sidewall construction.
In another prior structure, the sidewall structure of the stackable bin is of a two-ply construction formed by two layers of fluted plastic bonded together, with elongate metal rods of cylindrical cross section inserted vertically into some of the individual flutes in an attempt to increase vertical stacking strength. This constructional arrangement, however, is undesirable since not only is insertion of small cross section metal rods into the flutes a difficult and time consuming operation, but it has been observed that these metal rods are often dislodged, i.e., they tend to slide longitudinally within the flutes, and hence make handling of the sidewall structure more difficult.
While the Assignee's prior structures as explained above have performed in a highly-desirable manner, nevertheless the present invention was developed so as to continually improve upon the sidewall structure associated with stackable bins of this type.